EP2506673A2 - Domestic appliance - Google Patents

Abstract

The household appliance (10) has a main structure (12) comprising four load elements (20,22,24,26) that are arranged below a hob plate (14). A power module (18) is provided to supply power to load elements. Die Verbraucher 20, 22, 24, 26 sind unter einer Kochfeldplatte 14 angeordnet.A switching unit is provided to selectively connect the power converters with respect to load elements. A control unit (34) is provided to control the operation section of the load elements. An independent claim is included for method for operating household appliance.

Description

The invention relates to a domestic appliance device according to the preamble of claim 1.

Induction hobs are known in which an inverter supplies two induction heating units with power in temporal change. An electric power that draws an induction heating unit from the inverter depends both on a frequency of a high-frequency alternating current, with which the inverter supplies the induction heating units, as well as on a material of a Gargutbehältnisses, which is to be heated with the induction heating unit.

The object of the invention is in particular to provide a home appliance device with a long service life. The object is achieved by the features of claim 1, while advantageous embodiments and modifications of the invention can be taken from the dependent claims.

The invention is based on a domestic appliance device with at least one first consumer, which is intended to be operated in sections in at least one operating mode, and which in an operating section of a power converter relates to a dependent of at least one internal and at least one external operating characteristic electrical power.

It is proposed that the home appliance device comprises a control unit which is provided to set the internal operating parameter to at least one safety value at the beginning of the operating section in at least one safety section. An "internal operating parameter" is to be understood in particular to mean a parameter of the domestic appliance device which advantageously characterizes an operating state of the domestic appliance device and which can preferably be changed at least by the control unit and / or by operating elements of the domestic appliance device. An "external operating parameter" is to be understood, in particular, as a characteristic which indicates an operating state of the household appliance device Characterized and which differs from an internal operating characteristic, in particular a characteristic which is dependent on properties of a cooking utensil placed in and / or on a domestic appliance, in particular a cooking surface of the domestic appliance, in particular a position and / or a material of the cooking utensil. A "consumer" is to be understood in particular as a unit which has at least one consumer element which converts an electrical power into another power form, preferably a heating power. In particular, in an operating state in which the consumer obtains electrical power, all consumer elements of the consumer, preferably simultaneously, receive electrical power. A "power converter" should be understood to mean, in particular, a unit which converts an electrical power having specific parameters, in particular a rectified mains alternating voltage, into an electrical power having other characteristics, in particular an alternating current having a frequency which is greater than a frequency of a mains alternating voltage , An "operating section" should be understood to mean in particular a period during which a consumer obtains electrical power, in particular at least 1 W, in particular advantageously at least 10 W, particularly advantageously at least 20 W and preferably at least 50 W from the power converter. In particular, an operating section has a duration of at least 50 ms, advantageously at least 60 ms, and preferably at least 90 ms. A "control unit" is to be understood as meaning, in particular, an electronic unit which is preferably provided to control and / or regulate at least the power converter. The control unit preferably comprises a computing unit and, in particular in addition to the computing unit, a memory unit with a control and / or regulating program stored therein, which is intended to be executed by the computing unit. The term "intended" is to be understood in particular to be specially designed and / or specially equipped and / or specially programmed for this purpose. In particular, the security section has a duration of at least 1 ms, advantageously at least 2 ms, and preferably at least 8 ms. Preferably, the control unit is provided to set the value of the internal operating characteristic to an operating value in a part of the operating section after the safety section. In particular, an "operating value" is to be understood as meaning a value of the internal operating parameter, in particular a frequency of a high-frequency alternating current, in which the consumer obtains electrical power from the power converter, with one from an operator requested active power of the consumer, in particular a desired heating power, can be achieved during the operating section and in which an operation of the power converter takes place within the load limits of the power converter.

Preferably, the control unit is provided to set the value of the internal operating parameter to at least one safety value at a beginning of the operating section of the first consumer only if the operating value of the internal operating parameter in the operating section of the first consumer is outside a safety range and / or the operating value in an immediately preceding operating section of the first consumer was outside the safety area. By "immediately preceding" is to be understood in particular that temporally between the immediately preceding operating section of the first consumer and a current operating section of the first consumer only operating states of the home appliance device are different, which are different from an operating section of the first consumer. In particular, an immediately preceding operating section is spaced apart from an operating section for a maximum of 7 s, advantageously for a maximum of 5 s and preferably for a maximum of 2 s. In particular, a "safety value" is to be understood as meaning a value of the internal operating parameter in which, independently of a value of the external operating parameter, operation of the power converter can take place within load limits of the power converter. In particular, a "safety area" should be understood as meaning all values of the internal operating parameter which are safety values. In particular, "adjust" should be understood to mean that the control unit controls the power converter such that a change in the value of the internal operating characteristic to a value to be set for the internal operating parameter can be achieved. In particular, a long service life of the domestic appliance device can be achieved by avoiding damage to the power converter by a value of the external operating characteristic changed in an operating state before the operating section and a resulting operation of the power converter outside of load limits.

Furthermore, it is proposed that the internal operating characteristic of an operating characteristic of the power converter, in particular a performance characteristic of the power converter, in particular a frequency of a high-frequency alternating current of the power converter is formed. In particular, a quick adjustment of the internal operating characteristic can be achieved.

Furthermore, it is proposed that the security section has a duration that corresponds to a maximum of 50 percent, advantageously not more than 40 percent and preferably not more than 20 percent of a duration of the operating section. In particular, the security section has a maximum duration of 30 ms, advantageously a maximum of 20 ms, and preferably a maximum of 17 ms. In particular, a long duration of the proportion of the operating section in relation to the security section can be achieved, in which the desired active power of the consumer can be achieved.

It is also proposed that the domestic appliance device according to the invention has a sensor which is provided for measuring a performance characteristic of the power converter during the safety section. A "sensor" is to be understood in particular as an element, preferably an electrical component, which is provided for transferring a measured variable, in particular a performance variable, preferably a performance characteristic of a power converter, into another physical, preferably electrical, size, in particular a digital signal. where there is a one-to-one correspondence between the physical quantity and the measurand in at least one application area. Preferably, the sensor has a signal connection to the control unit, which differs in particular from a power supply connection of the sensor. A "performance characteristic" should be understood to mean, in particular, an electrical parameter, preferably a magnitude of an electrical current, an electrical voltage and / or the electrical power. In particular, the operating value can be determined from the measurement of the performance characteristic and thus safe operation of the home appliance device can be achieved.

Furthermore, it is proposed that the control unit is provided to adapt the internal operating parameter from a start value to the safety value in a start section. A "start value" is to be understood in particular as meaning a value of the internal operating parameter which is within the safety range and, in particular, is different from the safety value. The adaptation from the starting value to the safety value preferably takes place continuously, in particular monotone, preferably linear. Preferably, the start value is formed from an extremal value of the safety values that the internal operation characteristic assumes in the safety section. Preferably, the starting value is formed by an extremal value of the security area. In particular, a uniformly increasing load of the power converter during the safety section can be achieved by the starting section, whereby a long service life of the power converter and the home appliance device can be achieved.

Furthermore, it is proposed that the starting section has a duration which corresponds in particular to a maximum of 60 percent, advantageously not more than 30 percent and preferably not more than 5 percent of the duration of the security section. In particular, the starting section has a duration of at least 100 μs, advantageously at least 200 μs and preferably at least 300 μs and at most 1 ms, advantageously at most 800 μs and preferably at most 700 μs. In particular, safe operation of the power converter at the beginning of the safety section can be achieved.

It is further proposed that the home appliance device has at least one second consumer, which is intended to receive electrical power from the power converter in at least one operating mode in at least one operating section, which differs in time from an operating section of the first consumer. Preferably, the domestic appliance device has at least one switching element via which at least the first consumer and / or at least the second consumer receive electrical power from the power converter. Preferably, in an operating section of the first consumer, only the first consumer receives electrical power from the power converter via the at least one switching element. Preferably, in an operating section of the second consumer, only the second consumer receives electrical power from the power converter via the at least one switching element. Preferably, the home appliance device has at least one third consumer, in particular at least one further power converter, and a switching arrangement which is provided, preferably by switching commands of the control unit, at least three, in particular at least six, advantageously at least ten, different combinations of at least one of the at least one Power converter and at least one of the at least three consumers to connect directly. In particular, the switching arrangement has at least two Switching elements, in particular both are arranged between the first load and the first power converter. Under the fact that the switching elements are arranged "between" the power converter and the consumer, should be understood in particular that in an operating condition in which the consumer is supplied with high-frequency alternating current, the consumer with the switching means in any order on a single contact, preferably a voltage tap, the power converter is arranged in series. Preferably, in any operating state, the first switching element to the power converter, directly connected to the first switching element, the second switching element and the second switching element of the consumer. A "direct connection" is to be understood in particular as meaning an electrical connection which, at least in an operating state with a current flow of alternating current via the connection with a frequency between 1 kHz and 100 kHz, has an impedance which is smaller than its magnitude 10 V / A, in particular less than 1 V / A, preferably less than 0.1 V / A and whose amount fluctuates in particular over a frequency range from 1 kHz to 100 kHz by a maximum of 10%, preferably a maximum of 3%. In particular, a component-saving construction of the domestic appliance device can be achieved, with in particular fewer power converters being required as consumers.

It is further proposed that at least the first consumer of an induction heating unit and the power converter are formed by a heating frequency unit. An "induction heating unit" is to be understood in particular as a unit having at least one induction heating element. In particular, in an operating state in which the induction heating unit is supplied with high-frequency alternating current, all induction heating elements of the induction heating unit, preferably simultaneously, supplied with high-frequency alternating current. An "induction heating element" is to be understood in particular as a wound electrical conductor, preferably in the form of a circular disk through which high-frequency alternating current flows in at least one operating state. The induction heating element is preferably provided to convert electrical energy into an alternating magnetic field, which is provided in a metallic, preferably at least partially ferromagnetic, heating means, in particular cooking utensils, eddy currents and / or remagnetization effects which are converted into heat. A "heating frequency unit" should in particular be understood to mean an electrical unit which generates an oscillating electrical signal, preferably at a frequency of at least 1 kHz, in particular of at least 10 kHz, advantageously of at least 20 kHz, and in particular of not more than 170 kHz for an induction heating unit , In particular, the heating frequency unit is provided to provide a maximum electrical power of at least 1000 W, in particular at least 2000 W, advantageously at least 3000 W, and preferably at least 3500 W, required by the induction heating unit. The heating frequency unit comprises in particular at least one inverter, which preferably has at least two, preferably series-connected, bidirectional unipolar switches which are formed in particular by a transistor and a diode connected in parallel, and particularly advantageously at least one damping capacitor connected in parallel to the bidirectional unipolar switches, which is in particular formed by at least one capacitor. As a result, a high-frequency power supply of the induction heating unit can be provided. A voltage tap of the radio-frequency unit is arranged in particular at a common contact point of two bidirectional unipolar switches. In particular, an induction heater with a long service life can be provided.

It is further proposed a domestic appliance with a domestic appliance device according to the invention. In particular, the domestic appliance is designed as a hob, preferably as an induction hob, and / or in particular as an oven, preferably an induction oven, with in particular a hob device, preferably an induction hob device.

Further advantages emerge from the following description of the drawing. In the drawings, embodiments of the invention are shown. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1:

ein als Induktionskochfeld ausgebildetes Hausgerät mit einer erfindungsgemäßen Hausgerätevorrichtung in einer schematischen Darstellung von oben,

Fig. 2:

eine als Induktionsheizvorrichtung ausgebildete erfindungsgemäße Hausgerätevorrichtung des Hausgeräts aus Figur 1 in einer schematischen Darstellung,

Fig. 3:

eine schematische Darstellung eines beispielhaften Leistungsverlaufs der erfindungsgemäßen Hausgerätevorrichtung aus Figur 2 und

Fig. 4:

eine schematische Darstellung eines Verlaufs einer Leistung eines Leistungswandlers der Hausgerätevorrichtung aus Figur 2 in Abhängigkeit von einer Frequenz eines hochfrequenten Wechselstroms des Leistungswandlers, dargestellt für mehrere verschiedene Gargeschirre.

Show it:

Fig. 1:

a home appliance designed as an induction hob with a domestic appliance device according to the invention in a schematic representation from above,

Fig. 2:

a home appliance device according to the invention designed as an induction heater of the domestic appliance FIG. 1 in a schematic representation,

3:

a schematic representation of an exemplary performance curve of the home appliance device according to the invention FIG. 2 and

4:

a schematic representation of a curve of a power of a power converter of the home appliance device FIG. 2 as a function of a frequency of a high-frequency alternating current of the power converter, shown for several different cooking utensils.

Fig. 1 shows a designed as an induction hob home appliance 10 with a designed as an induction hob device household appliance device 12 with four formed as induction heating units consumers 20, 22, 24, 26, each having a designed as an inductor load element. The consumers 20, 22, 24, 26 are arranged under a hob plate 14. Furthermore, the domestic appliance device 12 has a power module 18 operated by a single phase 16 of a three-phase domestic connection, which is provided to supply the consumers 20, 22, 24, 26 with high-frequency alternating current with a frequency between 20 kHz and 170 kHz. For this purpose, the power module 18 has two power converters 30, 32, which are intended to be operated via the single phase 16 and to supply the loads 20, 22, 24, 26 ( Fig. 2 ). The frequency of the power converters 30, 32 depends inter alia on a heating power demanded for the loads 20, 22, 24, 26 via an operating unit 28 and a cooking utensil which is arranged in a cooking zone on the hob plate 14 above the consumer 20, 22, 24, 26 is arranged. The home appliance device 12 has a control unit 34, which among other things determines the frequency of the power converters 30, 32. The control unit 34 has an arithmetic unit, a memory unit and an operating program stored in the memory unit, which is intended to be executed by the arithmetic unit.

FIG. 2 shows the trained as induction hob device household appliance device 12 in a schematic representation. A voltage applied to a phase 16 between 220 V and 230 V mains voltage with a network frequency between 49 Hz and 51 Hz is rectified in a rectifier 36 and stored in a buffer capacity 38 partially. The poles of the buffer capacitor 38 form two external contacts 40, 42 between which a pulsating DC voltage is applied. The power converters 30, 32 are arranged between the external contacts 40, 42 and convert the pulsating DC voltage into high-frequency alternating current. For this purpose, the power converters 30, 32 each have two switching elements 44, 46 which are connected in series between the external contacts 40, 42 and designed as bidirectional unipolar switches, each having a parallel-connected damping capacitor 48, 50. The switching elements 44, 46 are each formed by an IGBT 52, 54 (insulated gate bipolar transistor) and a parallel connected diode 56, 58. A voltage tap 60, 62 is arranged in each case at a common contact of the two IGBTs 52, 54. The control unit 34 causes by alternating, high-frequency control of the two IGBTs 52, 54 at the voltage tap 60 a high-frequency alternating voltage with pulsating amplitude, which follows a high-frequency alternating current when connecting a consumer 20, 22, 24, 26. The voltage taps 60, 62 of the power converters 30, 32 are connected to a switching arrangement 64 having six relay elements formed switching elements 66, 68, 70, 72, 74, 76, which are designed as a single pole changeover switch, and by switching commands of the control unit 34 thereto it is intended to directly connect 16 different combinations of up to two of the two power converters 30, 32 and up to two of the four loads 20, 22, 24, 26. As one-pole changeover switch formed switching elements 66, 68, 70, 72, 74, 76 each have three contacts and two switching states. In a first switching state, the first contact is directly connected to the second contact and in a second switching state, the first and the third contact are directly connected (in the illustration, the first contact is arranged on the left and the second contact on the top right). The switching elements 66, 68, 70, 72, 74, 76 are arranged in a cascaded circuit. A first contact of the switching element 66 is directly connected to the voltage tap 60 of the power converter 30. A second and a third contact of the switching element 66 is in each case directly connected to a first contact of the two switching elements 68, 70. The consumers 20, 22, 24, 26 are each directly connected to one of the second or third contacts of the switching elements 68, 70. At the voltage tap 62 of the second power converter 32 is connected with the switching elements 72, 74, 76 a similar arrangement. Each of the loads 20, 22, 24, 26 can thus be directly connected to each of the power converters 30, 32 by suitable switching states of the switching elements 66, 68, 70, 72, 74, 76. Furthermore, any two of the loads 20, 22, 24, 26 may be directly connected to different power converters 30, 32 simultaneously. Likewise, for each of the consumers 20, 22, 24, 26, a boost operation in which a single load 20, 22, 24, 26 is directly connected to both power converters 30, 32 simultaneously is possible. The consumers 20, 22, 24, 26 are each operated in half-bridge circuit. Consumers 20, 22, 24, 26 each have a common contact 78, 79 which is in each case connected directly to a resonance unit 80, 81 which is formed by two resonance capacitances 82, 84 and 83, 85 formed from individual capacitors. The resonant capacitances 82, 84 and 83, 85 are each connected in series and one of the resonant capacitances 82, 83 is connected directly to one of the external contacts 40 and the other of the resonant capacitors 84, 85 is connected directly to the other external contact 42. Both of the resonance capacitances 82, 84 and 83, 85 are each connected directly to the two loads 20, 22 and 24, 26, respectively. The home appliance device 12 thus has a control unit 34, a first and a second load 20, 22 and a first and a second power converter 30, 32, which in an operating mode in which the first load 20 is connected directly to the first power converter 30 and the second load 22 is connected directly to the second power converter 32 via which two loads 20, 22 are connected. Furthermore, it is possible for the power converters 30, 32 to be connected via the third and the fourth consumers 24, 26. Furthermore, the domestic appliance device 12 has two sensors 86, 88, which are provided for determining a performance characteristic. The performance characteristic is formed by a peak value of a current flowing across the voltage tap 60, 62 of the power converters 30, 32. The sensors 86, 88 are formed as an ammeter with analog-to-digital converters, each connected directly to the voltage tap 60, 62 of the power converter 30, 32 and the first contact of the switching elements 66, 72 of the switching device 64 and thus between a consumer 20, 22nd , 24, 26 and a power converter 30, 32 are arranged.

FIG. 3 shows in a diagram a schematic representation of an exemplary profile of the frequency f of a high-frequency alternating current, the first consumer 20 and the second consumer 22 relate from the power converter 30, in Depending on a time t and in another diagram is a schematic representation of an exemplary course of the power P, which the consumers 20, 22 relate to the power converter 30, as a function of the time t. The diagrams represent a section of an exemplary operating mode of the domestic appliance device 12 according to the invention. In this exemplary operating mode, the first consumer 20 and the second consumer 22 are operated in sections, with operating sections 90, 94 of the consumers 20, 22 being free of overlapping. In this case, in the operating section 90, 94, the load 20, 22 receives an electric power from the power converter 30, which is dependent on an internal operating characteristic and on an external operating characteristic. The internal operating characteristic is determined by an operating characteristic of the power converter 30, a frequency f of the high-frequency alternating current the consumer 20, 22 of the power converter 30, formed. The external operating characteristic is in each case formed by a coupling of the consumer 20, 22 with a cooking utensil which is set up on a heating zone associated with the consumer 20, 22, which depends on material properties of the cooking utensil and a position of the cooking utensil on the heating zone.

At a beginning of the operating section 90 of the first load 20, the frequency f of the high-frequency alternating current is _adjusted by the control unit 34 during a safety section 91 in a start section 92 from a start value f _START1 of 170 kHz to a safety value f _S1 of 35 kHz. The operating section 90 of the first load 20 has a duration of 93 ms, the safety section 91 a duration of 16.5 ms, ie 17.7% of the duration of the operating section 90, and the start section 92 has a duration of 350 μs, ie 2 , 1 percent of a duration of the security section 91. At one end of the security section 91, the frequency f of the high-frequency alternating current is set from the safety _value f _S1 of 35 kHz to an operating _value f _Op1 of 25 kHz via the control unit 34. At one end of the operating section 90 of the first load 20, the control unit 34 _adjusts the frequency f of the high-frequency alternating current from the operating _value f _Op1 of 25 kHz to a stop value f _STOP1 of 130 kHz. In the following switching section 93, which has a duration of 7 ms, no high-frequency alternating current is generated by the power converter 30. In this switching section 93, the switching arrangement 64 is switched over from a connection of the power converter 30 to the first load 20 to a connection of the power converter 30 to the second load 22 Following operation section 94 of the second consumer 22, a security section 95 is switched by the control unit 34. The operating section 94 has a duration of 1893 ms, the security section 95 a duration of 16.5 ms, ie 0.08% of the duration of the operating section 94. At a beginning of the safety section 95, the frequency f of the high-frequency alternating current becomes the second Consumers 22 of the power converter 30, adapted in a start portion 96 of a start value f _START2 of 170 kHz to a safety value f _S2 of 35 kHz. The start section 96 has a duration of 700 μs, ie 4.2 percent of the duration of the safety section 95. At one end of the safety section 95, the frequency f of the high-frequency alternating current from the safety _value f _S2 of 35 kHz to the operating _value f _Op2 of _FIG kHz adjusted. At one end of the operating section 94, the frequency f of the high-frequency alternating current is _adjusted by the control unit 34 from the operating _value f _Op2 of 29 kHz to a stop value f _STOP2 of 120 kHz. This is followed by a switching section, not shown in the diagram, in which, as in the switching section 93, a power supply through the power converter 30 is interrupted and in which a switching of the switching arrangement 64 from the connection of the power converter 30 with the second load 22 to the connection of the power converter 30 takes place with the first consumer 20, whereupon repeats the sequence shown schematically in the diagram. Such a repetition of the schematically illustrated process takes place periodically with a period of 2 s. Alternatively, other modes of operation are possible in which a different number of consumers, in particular one, three or more, are operated in temporally spaced-apart operating sections. Alternatively, other values of the frequencies, in particular other safety values, are possible. In particular, the safety values depend on the parameters of the consumer.

FIG. 4 schematically illustrates an exemplary course of the power P of a circuit comprising the power converter 30 and at least the load 20, depending on the frequency f of the high-frequency alternating current of the power converter 30, the first load 20 from the power converter 30 relates and in response to a Coupling to a cooking utensil, which is positioned on the first consumer associated heating zone. The exemplary course is shown in three different curves 1, 2 and 3 for several different cookware, which, due to different properties, such as different material properties or different sizes of cookware, have a different coupling to the circuit. In the exemplary course the power P as a function of the frequency f is a safety value f _{s of} the frequency f drawn. Furthermore, the maximum power P _{max is} plotted, which characterizes an operation of the power converter 30 within load limits. A power of the power converter 30 may briefly exceed the maximum power P _max before damage to the power converter 30 occurs. Furthermore, in the FIG. 4 the limit frequencies f _ZVS1 , f _ZVS2 and f _{ZVS3 associated with} the curves 1, 2 and 3, which designate the lower limits of the frequency f of the high-frequency alternating current at which safe operation of the power converter 30 is possible.

It is assumed that an operating state in which a cooking utensil was heated in a previous operating section on a heating zone associated with the first consumer 20, which can be described by the curve 2. In the previous operating state, the power converter 30 was operated at an operating frequency f _Op at which a power of the power converter is lower than the maximum power P _max . If, during an operating state in which the first consumer does not receive power from the power converter 30, an exchange of the cooking utensil, then in a further operation of the power converter 30 with the operating frequency f _Op in the following operating section could exceed the maximum power P _max or _{fall below} the cut-off frequency f _ZVS occur, so that damage to the power converter 30 may occur. Therefore, at the beginning of an operating section, a safety section is switched by the control unit 34 in which the frequency f has a safety value f _s . Like from the FIG. 4 As can be seen, the safety frequency f _{s is} higher than the limit frequencies f _ZVS1 , f _ZVS2 , and f _ZVS3 , so that when replacing the cooking utensil safe operation of the power converter 30 is ensured.

In the event that the cooking utensil described by the curve 2 is exchanged for a cooking utensil, which is described by the curve 1, a safe operation of the power converter 30 is ensured even with the operating frequency f _Op , since both the _Limit frequency f _ZVS1 lower than the operating frequency f _Op is as well as the occurring at the operating frequency f _Op power is less than the maximum power P _max . Due to the replacement of the cookware, a lower than the operator requested power at the operating frequency f _{Op is} achieved. In the security section, the frequency f from the control unit 34 to the Safety value f _s set. Compared to the course of the power curve 2, there is now a drop in performance. The sensor 86 performs a measurement of the peak value of the current flowing through the voltage tap 60 of the power converter 30 during the safety section (FIG. FIG. 2 ). This peak value is lower due to the power drop than a peak that would be measured at a power curve after the curve 2. The control unit 34 determines from the measured peak value a value for a changed operating frequency with which a heating power requested by an operator via the operating unit 28 and a safe operation of the power converter 30 can be achieved.

In the event that the cooking utensil described by the curve 2 is exchanged for a cooking utensil, which is described by the curve 3, with a maintenance of the operating frequency f _Op safe operation of the power converter 30 would not be ensured because at the operating frequency f _Op in the curve 3 both the cutoff frequency f _ZVS3 and the maximum power P _{max is} exceeded. By setting the frequency f of the high-frequency alternating current to the safety value f _s , safe operation of the power converter 30 is ensured, since the safety _value f _{S of} the frequency f is higher than the limit frequency f _ZVS3 . Exceeding the maximum power P _max occurs, which, however, can be tolerated in a short period of time, such as the safety section. Furthermore, by measuring the peak value of the current flowing through the voltage tap 60 of the power converter 30, the control unit 34 determines a new operating frequency with which the heating power requested by the operator via the operating unit 28 during the operating section and reliable operation of the power converter 30 are achieved can. Alternatively, safety values are also possible in which, when replacing the cooking utensils, the power occurring in the safety section is higher than without replacement of the cooking utensils, but the limit frequency f _ZVS is not exceeded. Alternatively, it is possible to dispense with a circuit of the safety section, if an operating value for possible cookware can be used as a safety value.

In principle, it is possible to provide a starting section in which a value of the frequency f is adjusted from a starting value to the operating value when a security section is omitted.

reference numeral

10

household appliance

12

Home appliance device

14

Hotplate

16

phase

18

power module

20

consumer

22

consumer

24

consumer

26

consumer

28

operating unit

30

power converter

32

power converter

34

control unit

36

rectifier

38

buffering capacity

40

outside Contact

42

outside Contact

44

switching element

46

switching element

48

snubber capacitor

50

snubber capacitor

52

IGBT

54

IGBT

56

diode

58

diode

60

voltage tap

62

voltage tap

64

switching arrangement

66

switching element

68

switching element

70

switching element

72

switching element

74

switching element

76

switching element

78

Joint contact

79

Joint contact

80

resonance unit

81

resonance unit

82

resonant capacitance

83

resonant capacitance

84

resonant capacitance

85

resonant capacitance

86

sensor

88

sensor

90

operating section

91

security section

92

start section

93

switching section

94

operating section

95

security section

96

start section

Claims (10)

Home appliance device with at least one first consumer (20, 24) which is intended to be operated in sections in at least one operating mode, and in an operating section (90, 94) of a power converter (30, 32) one of at least one internal and at least one external operating characteristic dependent electrical power, characterized by a control unit (34) which is provided at the beginning of the operating section (90) in at least one security section (91) set the internal operating characteristic to at least one safety value. Home appliance device according to claim 1, characterized in that the internal operating characteristic of an operating characteristic of the power converter (30, 32) is formed. Home appliance device according to one of the preceding claims, characterized in that the security section (91) has a duration which corresponds to a maximum of 50 percent of a duration of the operating section. Home appliance device according to one of the preceding claims, characterized by a sensor (86, 88), which is provided for measuring a performance characteristic during the security section (90). Domestic appliance device according to one of the preceding claims, characterized in that the control unit (34) is provided for adapting the internal operating parameter from a starting value to the safety value in a starting section (92, 96). Domestic appliance device according to claim 5, characterized in that the starting portion (92, 96) has a duration which corresponds to a maximum of 60 percent of a duration of the security section. Domestic appliance device according to one of the preceding claims,
characterized by at least one second load (22, 26) provided, in at least one operating mode, in at least one operating section (94) that differs in time from operating sections (90) of the first load (20, 24) from the power converter (30, 32) to obtain electrical power. Domestic appliance device according to one of the preceding claims, characterized in that at least the first consumer (20, 24) as an induction heating unit and at least the power converter (30, 32) are designed as Heizfrequenzeinheit. Domestic appliance having a domestic appliance device (12) at least according to claim 1. Method for operating a household appliance device (12) according to at least claim 1.

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